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"Particle swarm based design of variable structure stabilizer for a nonlinear model of SMIB system"
Get PDFIn this paper, a particle swarm-(PSO) based variable structure stabilizer (VSC) is proposed for enhancing the dynamic stability of a nonlinear model of synchronous machine infinite busbar system (SMIB). Unlike the methods reported in the literature which involve either linearizing the model of synchronous machine around a suitable operation point or applying nonlinear transformation techniques before linear control theory is used in designing a fixed parameter PSS, the present method formulates the design of VSC as an optimization problem and utilized the PSO algorithm to provide a simple and systematic way of arriving at the optimal feedback gains and switching vector values of the stabilizer. When compared to previous methods, simulation results showed the effectiveness of the proposed stabilizer design
"Large signal analysis of wideband non-linear amplifiers with sum and difference frequency injection"
Get PDFLarge signal analysis of a wideband non-linear amplifier excited by a multisinusoidal signal is presented. The special cases of two equal-amplitude sinusoids and their injected harmonics, sum- and difference-frequency components are considered in detail and the results are compared, whenever possible, with previously published simulation and experimental results
A High-Speed Self-Timed Carry-Skip Adder
No full textAn efficient self-timed carry-skip adder with low area overhead and fast operation is proposed. The adder combines delay-insensitive and bounded delay completion signal detection techniques to define a novel, reliable, area-efficient and high-speed completion-detection circuit. The circuit employs double-rail encoded carry signals together with process-tracking delay circuit elements to efficiently produce a final completion signal of tight acknowledge slack time under different operating conditions. In addition the proposed adder employs carry-skip speed-up circuitry resulting in a novel self-timed carry-skip adder that is quite efficient in terms of both speed and are
Efficient static compaction techniques for sequential circuits based on reverse-order restoration and test relaxation
Get PDFThe authors present efficient reverse-order-restoration (ROR)-based static test compaction techniques for synchronous sequential circuits. Unlike previous ROR techniques that rely on vector-by-vector fault-simulation-based restoration of test subsequences, the authors’ technique restores test sequences based on efficient test relaxation. The restored test subsequence can be either concatenated to the compacted test sequence, as in previous approaches, or merged with it. Furthermore, it allows the removal of redundant vectors from the restored subsequences using a state traversal technique and incorporates schemes for increasing the fault coverage of restored test subsequences to achieve an overall higher level of compaction. In addition, test relaxation is used to take ROR out of saturation. Experimental results demonstrate the effectiveness of the proposed techniques
An Analytical Tool to Assess Readiness of Existing Networks for Deploying IP Telephony
Get PDFDeploying IP telephony or voice over IP (VoIP) is a major and challenging task. This paper describes an analytical approach and tool to assess the readiness of existing IP networks for the deployment of VoIP. The analytical approach utilizes queueing network analysis and investigates two key performance bounds for VoIP: delay and bandwidth. The analytical tool is GUI-based and has an engine that automates the analytical approach. The engine determines the number of VoIP calls that can be sustained by a given generic network while satisfying VoIP QoS requirements and leaving adequate capacity for future growth. As a case study, the paper illustrates how the analytical tool can assess the readiness to deploy VoIP for a typical network of a small enterprise
"Performance of Cavity Backed Inverted Microstrip Broadband Antenna"
Get PDFAn inverted microstrip circular patch with a parasitic element printed back to back on the same substrate and backed by a cylindrical metallic cavity is investigated as a compact integratable broadband antenna. The cavity effect in changing its impedance behavior is thoroughly examined and an optimized X-band design is presented. As much as 11% bandwidth is apparent from the design data. Principal plane radiation patterns are also examined showing above 98 % efficiency and 10.97 dB directivity
Digital Image Watermarking Using Balanced Multiwavelets
Get PDFIn this paper, a robust watermarking algorithm using balanced multiwavelet transform is proposed. The latter transform achieves simultaneous orthogonality and symmetry without requiring any input prefiltering. Therefore, considerable reduction in computational complexity is possible, making this transform a good candidate for real-time watermarking implementations such as audio broadcast monitoring and DVD video watermarking. The embedding scheme is image adaptive using a modified version of a well-established perceptual model. Therefore, the strength of the embedded watermark is controlled according to the local properties of the host image. This has been achieved by the proposed perceptual model, which is only dependent on the image activity and is not dependent on the multifilter sets used, unlike those developed for scalar wavelets. This adaptivity is a key factor for achieving the imperceptibility requirement often encountered in watermarking applications. In addition, the watermark embedding scheme is based on the principles of spread-spectrum communications to achieve higher watermark robustness. The optimal bounds for the embedding capacity are derived using a statistical model for balanced multiwavelet coefficients of the host image. The statistical model is based on a generalized Gaussian distribution. Limits of data hiding capacity clearly show that balanced multiwavelets provide higher watermarking rates. This increase could also be exploited as a side channel for embedding watermark synchronization recovery data. Finally, the analytical expressions are contrasted with experimental results where the robustness of the proposed watermarking system is evaluated against standard watermarking attacks
Efficient Sample Rate Conversion for Software Radio Systems
No full textAn efficient sample rate conversion (SRC) method for software radio (SWR) systems is proposed. The proposed method modifies conventional single- or multistage SRC processes such that the computation of the output of a particular stage is performed in a hierarchical fashion. This SRC method consumes fewer computations than traditional SRC methods over a range of SRC factors and is especially suitable for SWR base station transmitters. The computational requirements of the proposed SRC method and conventional SRC methods are compared and simulation results of the proposed method are discussed
A Digital Clock Re-Timing Circuit for On-Chip Source-Synchronous Serial Links
Get PDFA new all-digital circuit scheme for clock and data re-timing functions for on-chip high-speed source synchronous data communications, such as in burst-mode data transmission over a network-on-chip is introduced. The new technique is non-PLL-based and is capable of retiming the output clock with the received data within one data transition. Being fully digital makes its area much smaller than conventional circuitry. It can also be described by any hardware description language, simulated, and synthesized into any digital process. This enables it to be ported from one technology to another and support system on a chip (SOC) designs. The design concept is demonstrated with T-Spice?? simulations using a 0.13??m digital CMOS technology